Unexpected
by Rajatarangini
Summary: When Regulus Sirius Black stumbles upon his older sister, Acquila, snogging Harry Potter, the evening doesn't go quite as planned. AU to Black Bond, based on a prompt from grandmasters-apprentice, written for Nerdman3000's birthday.


**Author's Note:** A big, big thank you to grandmasters-apprentice for the idea for this story. As you can guess from our long chapters, keeping a story short is a rather difficult thing for us, especially with a one-shot. But we've done our best.

Also, this is a birthday gift for Nerdman3000 :-)

 **oOo**

 **Unexpected**

Regulus Sirius Black had spent the entire day being a good, dutiful boy. He had put on his best dress robes, been on his best behaviour, he had helped Uncle Ted's old aunts to the table, danced with one of Dora's annoying Muggle cousins, tried his best to keep his younger brothers away from getting into any mischief.

But now, he decided he couldn't suppress the prankster in him anymore.

The wedding was over, everyone was busy dancing. _This_ was the time to do what he'd been itching to do all evening – light the huge pile of firecrackers that his best friend Stuart Longbottom and he had smuggled into the Tonks' new house.

Oh, Regulus knew his Mum and Aunt Lily would be mighty mad about the firecrackers. He knew all about He Who Must Not Be Named and the danger he posed to Remus and Dora's wedding (not just because Bellatrx Lestrange had sworn to kill her niece but also because werewolves like Remus couldn't marry under the new law brought in some years ago by Dolores Umbridge). His Mum would be mad and tell him that lighting the firecrackers wasn't a good idea at all when it could attract the attention of You Know Who and his Death Eaters. But Regulus had spoken to Uncle Peter about it, and Wormtail had assured him that the Tonks' house was well secured and even a huge cache of firecrackers wouldn't alert any Death Eaters to the location of the house.

"You ready?" Stuart whispered to him, smirking.

"Yes!" Regulus grinned. Downing the last of the Firewhiskey that he had slipped into his glass when his parents weren't looking, Regulus carefully scanned the wedding guests to make sure nobody was watching him.

His parents were dancing in a corner of the room. For once, Regulus' Dad looked relaxed and happy, unlike how worried he had looked lately with You Know Who's growing power. Sirius didn't look like either Auror Black or Lord Black tonight, despite the rich robes he had donned. He just looked like a normal man dancing with his wife, all grinning and carefree as he twirled Regulus' Mum, Athena, around. His Mum was looking beautiful too, with her auburn hair pulled up in a chignon and her bright eyes as she laughed at something his Dad said.

Uncle Ted and Aunt Andy were dancing too, as were the bride and the groom. Remus looked younger than he usually did, very dapper in his dress robes. Dora, meanwhile, was glowing with happiness, her bubblegum pink hair bright in the flickering magical lights that glowed all around the backyard.

Stuart's parents, Alice and Frank Longbottom, were sitting at one of the tables, talking to Kingsley Shacklebolt and Irene Summerby, their Auror colleagues.

Uncle James and Aunt Lily and their red-haired daughter Heather were busy trying to settle an argument between Regulus' seven year old twin brothers, Caelum and Charlus Black. Regulus was pretty glad he wasn't the one having to sort out one of the twin's many tiffs. For all that they were identical (from their McKinnon features right down to their bright blue eyes, quite unlike Regulus and Acquila who resembled their Black ancestors), his twin brothers were poles apart in their nature. Caelum was always quiet and calm like their Mum, while Charlus would surely grow up to be a bigger mischief-maker than all the Marauders combined, especially with Heather Potter as his partner in crime.

Uncle Peter, meanwhile, was sitting all alone in a corner. He seemed to have had a lot to drink already as he watched the dancing couples a little wistfully.

Acquila and Harry, though, were both missing… but it wasn't very suspicious seeing how often they were together. They were both the best of friends since childhood. Uncle James always joked that Harry had spent more of his childhood playing with Acquila at the Black's house than at his own home in Godric's Hollow.

Certain that everyone was too busy to notice them, Regulus and Stuart were about to leave when they saw Neville walking towards them.

"He knows!" groaned Stuart.

"He doesn't!" Regulus whispered. "Neville's cool."

For all that Neville claimed to be fed up of the pranks Stuart and Regulus pulled at Hogwarts, he knew the older Longbottom brother wouldn't tell on them to their parents. He was a pretty cool older sibling; Neville even joined Harry and Stuart and Regulus for Quidditch in the summer vacations… quite unlike Acquila who was more at home with books than broomsticks. It didn't help that Acquila was their Dad's favourite child, probably because she was Sirius' only daughter.

"Just because he plays Quidditch with us doesn't mean Neville's cool," Stuart whispered, reading Regulus' mind. "Acquila is way cooler, and she's so pretty too!" Stuart added dreamily.

"Don't talk about my sister like that!" groaned Regulus.

He knew Stuart had a crush on Acquila, as did a lot of other blokes at Hogwarts. Regulus couldn't why understand why boys were so crazy for Acquila. Agreed Acquila was quite pretty, but she could be so annoying at times, especially when she argued with Regulus on trivial matters and their Dad always took her side. She had already had two lame boyfriends that he knew of in the past two years, and she was only sixteen. What was worse was that many boys pretended to be friends with Regulus just to get a chance to talk to his sister, which never really worked but irritated him to no end.

"Why can't I talk about Acquila? It's the same as you talking about Larissa all the time," whispered Stuart.

"Larissa isn't your sister or something. And don't say that out loud!" said Regulus. "I don't want anyone knowing about Larissa."

Larrisa, despite being a Slytherin, was the coolest, prettiest girl in their year. Regulus had had a crush on her for months, but hadn't yet mustered the courage to ask her out.

"What are you two up to this time?" asked Neville, finally walking up to them.

"Nothing, we're just talking." Stuart shrugged.

"I know you both are up to something," Neville sighed. "I have my eye on you, alright? Don't do something stupid and ruin the day. It's a long time since we've had something to celebrate."

Neville stared at them a little sternly and then ruined the effect by ruffling Stuart's hair affectionately, and then left to talk to his parents.

"Do you think we should drop the plan?" asked Stuart quietly. For all that he loved pranks, Stuart could be a little meek at times.

"No." Regulus frowned. "It's just firecrackers. No big deal. Uncle Peter told me it's safe."

They waited for Neville to get busy, and then Regulus slipped out of the backyard and into the house, knowing Stuart would follow a couple of minutes later.

The house had been recently purchased by Uncle Ted and Aunt Andy after their old house had been blown up by the Lestranges. So, a very few people had been invited, keeping in mind the security concerns. With the War still going on for years now, it was better to be safe. Having so many Aurors and Order of the Phoenix members in one place at the same time was a little risky if they were attacked tonight, but Uncle James and Regulus' Dad, who were Head and Deputy Head of the Auror Department, had ensured that the Tonks' new house was as secured as could be for everyone to have one day of fun, away from all the worries that usually plagued them.

Eagerly imagining the fright and then the awe that everyone would feel on seeing the firecrackers they had charmed, Regulus took the stairs two at a time. But he had barely got up the staircase when he heard whispered voices from one of the rooms, making his heart race suddenly with fear. Everyone was out there in the backyard, so _who_ could be hiding in the rooms here?

Regulus' first instinct was to go back out and tell his Dad that there was someone in the house. But something, perhaps the Gryffindor in him, made him grab his wand, gather his courage and walk to the room at the end of the corridor, where he could see the light shining from the slightly ajar door.

His heart in his mouth and his palms clammy, Regulus crept soundlessly to the door, only to be surprised when he heard a girlish giggle from within.

"You never told me that before," said a familiar voice that belonged to his older sister. But Acquila had never sounded like this before, so awed and almost coy.

Regulus almost groaned. She had barely broken up with that Zabini, but Acquila had to go and get _another_ boy fancying her, didn't she? Who could it be, though? There weren't many boys her age invited to Remus and Dora's wedding, except Neville who was in the backyard and— _Great Godric,_ it couldn't be! It couldn't be _Harry,_ could it?

"But I _have_ always liked you," came another voice from inside the room. "I just never got a chance to tell you."

It _was_ Harry's voice! It was _Harry_! Harry was in there, with Acquila! Regulus could barely believe his ears!

"You never told me," said Acquila again.

"That was because you were busy mooning over Cedric Diggory and Blaise Zabini. I didn't think you would fancy me—"

"Oh, Harry," Acquila said softly, "I've always liked you… long before I dated Blaise and Cedric… I just thought you were too busy liking Daphne Greengrass to think of me—"

Acquila and Harry! Harry and Acquila! _Together_! Regulus felt like his head was spinning. When had that happened? How had Harry fallen for Acquila? And vice versa?

Everyone knew they had always been close, the very best of friends since they were mere toddlers. But them fancying each other? That was astonishing, because they had never once behaved like they even had a crush on the other!

Regulus felt like groaning aloud again. Why Harry? Though he wouldn't admit it to anyone, Regulus quite looked up to Harry. He was the best Seeker in Hogwarts, all the girls were crazy for him because Harry could be pretty charming when he wanted to (Dad said he had Uncle James to thank for that), and Harry was confident too, but pretty down to earth and really good at Transfiguration and DADA.

They had stopped talking now, Harry and Acquila. And Regulus decided to walk away from there. He would keep quiet about this, of course. Though he could use this in future some time, like when he wanted Acquila's help to help cajole his parents into buying him the expensive new broomstick that he'd had his eye on since some months now. Or perhaps he could go to the backyard and tell everyone what he had just heard. It would be fun watching their reactions. Oh, what a dilemma this was!

Harry and Acquila! Regulus still couldn't believe it, though now that he thought about it, the two of them had always been a little _too_ close… completing each other's sentences and walking hand in hand everywhere when they were younger, Acquila kissing Harry's cheek one time too many, and Harry grinning extra widely whenever he was with Acquila. Damn! How had he missed all the signs? But coming to think of it, Regulus preferred his sister being with Harry than a git like that Blaise Zabini. Harry was family.

The more he thought of it, the more Regulus found that he couldn't resist having a peek at the two love birds.

He opened the door a little, glad it opened noiselessly. But a moment later, he wished he hadn't wanted to look in.

Harry's hands were on Acquila's waist, while she had her arms around Harry's neck. They were looking at each other with sickeningly sweet expressions, and before Regulus knew it, they were snogging.

Regulus made to walk out of the room, only for his elbow to hit the wooden door painfully and _loudly._

Acquila and Harry jumped apart, hearing his loud _ouch!_ Acquila's grey eyes were wide with surprise when she spotted Regulus. Harry looked embarrassed now, running a hand through his hair; he wasn't quite meeting Regulus' gaze.

"Reggie!" exclaimed Acquila. "What are you doing here? Get out!"

"No, wait! We don't want anyone finding out yet, especially Uncle Sirius," said Harry.

Regulus quite wanted to laugh. His Dad doted on his godson, but he was quite sure he wouldn't take well to Harry dating his only daughter. No wonder Harry was sounding so uneasy at the thought of Sirius knowing he'd been snogging Acquila.

"Reggie, don't tell anyone, alright?" said Acquila, half-threatening, half-pleading. "If you do, I'll tell Mum you were the one who put the serpent venom into Aron Warrington's potion and made it blow up. Poor Daniel Summerby got blamed for that."

But Regulus didn't quite want to listen to her now. It would be such fun watching their parents' reaction to the news that Harry and Acquila were snogging! Oh, this would be such fun!

Without another word, Regulus fled down the stairs and onto the backyard, Harry and Acquila following him closely. He sped past a bewildered Stuart and straight to his Dad who was now sitting at a table with Mum and the Potters.

"Dad! You won't believe what I saw!" Regulus exclaimed loudly.

"What happened?" His Dad seemed concerned now, because his hand reached for his wand. "What's the matter, Reg?" His Dad asked him loudly, easily slipping into his Auror Black persona now.

Before Regulus knew it, half the wedding party had gathered around him, wondering what was wrong. Even Charlus, Caelum and Heather had stopped playing their game of hide and seek, the twins watching him with curious blue-eyed gazes. Regulus was sure if he would take any longer to reply all their wands would be out.

Uncle James too seemed concerned. "What's wrong, Reg?"

"It's Harry and Acquila!" Regulus exclaimed, pointing at the two lovebirds who stood glaring at him.

"You don't need to point at us, Reggie," said Acquila, huffing. "Everyone here knows who we are."

"They were _snogging_ , Dad!" exclaimed Regulus, ignoring her. "In the upstairs bedroom!"

"You were what?" asked Sirius sharply, his eyes narrowed as he stared at Harry and Acquila.

"They were snogging! _You never told me you fancied me,"_ Regulus said in a high-pitched voice that was meant to imitate Acquila.

Regulus' Dad stood up, staring at Harry, who was rather red in the face now. Acquila looked a little unsettled, but there was a defiant glint in her eyes.

Regulus wanted to rub his hands in glee. Oh, Harry was going to have it now. Their Dad hated the very thought of any boy with Acquila. After all, his Dad was the one who had told him the spell to make warts sprout all over Blaise Zabini's arms last term at Hogwarts and the charm to turn Cedric Diggory's hair a bright shade of green that didn't come off for almost a week.

"You were kissing Acquila?" said Sirius, advancing towards Harry now. Uncle James watched mutely. Regulus' Mum and Aunt Lily, though, were grinning widely, almost as if this was the best thing they'd heard all day.

"I was," said Harry, gulping visibly. "But I—I really like her, I do. I _always_ have…"

"You always have, huh?" said Sirius brusquely. "Then why did you take so long to tell her that, you foolish boy? Prongs and I have been waiting for this for so long!"

With that, Sirius pulled a bewildered Harry into a one-armed hug.

"We couldn't be happier, could we, Prongs?" said Regulus' Dad, as the two men high fived like they were teenagers, identical grins on their faces.

"We're going to be related now, Padfoot! Your daughter and my son!" exclaimed Uncle James, clapping Harry proudly on his back, while Regulus watched them both, gobsmacked.

"You're already related to each other," pointed out Acquila. "Your mother was a Black, Uncle James."

"But we'll be _properly_ related now! Welcome to the family, dear girl!" exclaimed Uncle James, still grinning like he'd won the Quidditch League Cup or something.

"You're all going way ahead with this!" protested Acquila. "It was just one kiss!"

But no one seemed to be listening.

"Oh, think of their wedding, Lily!" said Regulus' Mum. "We can plan it together when they're both of age!"

"And when they have children, we'll be grandmothers together!" said Aunt Lily, her eyes twinkling mischievously.

"Mum, this is ridiculous!" exclaimed Harry, his face as red as Acquila's now.

"Don't worry, sweetie," said Aunt Lily. "No pressure on either of you. We're all just excited, that's all."

"Yes, we're not going to poke our noses into your relationship or anything, love," said Athena. "But don't let go of Harry, alright, Acquila? He's such a good boy—"

"And we've been waiting for months and months for both of you to get together," put in Uncle James.

"All that tiptoeing around each other, and those coy glances—" said Aunt Lily.

"And all those needless complications with the Zabini boy and the Greengrass girl," said Regulus' Dad.

"We're just so happy, darlings," said Aunt Lily again, grinning widely.

Acquila and Harry looked like they didn't really know where to go from there or what to say for that matter. Truthfully, neither did Regulus. He hadn't anticipated this reaction at all.

His Dad and Uncle James were calling for more wine to celebrate now, while his Mum and Aunt Lily were discussing something that sounded suspiciously like how pretty the ancestral Potter family ring would look on Acquila's finger someday.

"Your parents are crazy," said Dora, chuckling. "I mean, sure, Sirius and James were always a little off. But even Lily and Athena? Interesting development, though. Keep me updated." Dora winked at Acquila, while Uncle Remus joined the two Marauders at the table, calling Uncle Peter to join them.

"Well, that was upsetting," Stuart said, sounding heartbroken. "Acquila and Harry, huh?"

"Come on, you knew you never had a chance with Acquila," said Regulus. "You wouldn't have lasted with her anyway. She's way too headstrong."

"Why are you smiling?" asked Stuart. "I thought you expected your Dad to yell at Harry or something, not celebrate him being his future son-in-law."

"I was imagining my Mum and Dad and Larissa's parents being just as happy if I ever manage to get her to date me," said Regulus, smiling at the thought of the girl.

"That's never going to happen," snorted Stuart. "Lucius Malfoy's daughter and Sirius Black's son. Both your fathers would rather fight a duel to the death than agree to have you date Larissa. And Draco Malfoy would pummel you with his bare hands like a Muggle than see you with his baby sister."

"Well, I can always hope," said Regulus hopefully. "Now let's go burst those firecrackers, eh? The celebrations aren't quite over yet." He grinned.

* * *

 _Lord Sirius Orion Black, Head of the House of Black_

 _His wife, Lady Athena McKinnon-Black_

 _Their daughter, Acquila Dorea Black, aged sixteen_

 _Their son, Regulus Sirius Black, aged fourteen_

 _Their twin sons, Caelum Edward Black and Charlus Alphard Black, aged seven_

 _James Charlus Potter, Head of the House of Potter_

 _His wife, Lily Potter_

 _Their son, Harry James Potter, aged sixteen_

 _Their daughter, Heather Lily Potter, aged eight_

 _Lord Frank Longbottom, Head of the House of Longbottom_

 _His wife, Lady Alice Longbottom_

 _Their son, Neville Longbottom, aged sixteen_

 _Their son, Stuart Longbottom, aged fourteen_

 _Lucius Malfoy, Head of the House of Malfoy_

 _His wife, Narcissa Malfoy_

 _Their son, Draco Malfoy, aged sixteen_

 _Their daughter, Larissa Malfoy, aged fourteen_

* * *

 **A/N:** Hope you enjoyed this! And for those who asked, yes, we've got back to regular writing, and we are working on chapter 2 of Black Bond II :-)


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